This invention relates to novel liquid, storage-stable, modified diphenylmethane diisocyanate compositions and to a process for the preparation of these novel liquid, storage-stable, modified diisocyanate compositions.
Polyisocyanate compositions exhibiting low viscosities and high functionalities and a process for their preparation are disclosed in U.S. Pat. No. 6,730,405. These polyisocyanate compositions may be reacted with a compound comprising a mobile hydrogen, which are also known as masking agents. Masking agents are described as having at least one functional group carrying a mobile (or reactive) hydrogen, and the functional group should have a pKa of at least 4 to less than or equal to 14.
U.S. Pat. Nos. 5,777,023 and 5,881,648 disclose diamidediurethanes and hot melt printing from hot melt inks comprising these diamidediurethanes. The diamidediurethanes are prepared by reaction of a hydroxycarboxylic acid and/or lactone with either (1) monoamine and diisocyanate, or (2) diamine and monoisocyanate. These may also be prepared by reacting a non-hydric carboxylic acid and/or anhydride with a hydroxylamine and a diisocyanate. These products are solids. Also, the products are diurethanes, end-capped with an amide group.
It has surprisingly been found that diisocyanates which are modified with a compound containing both an amide and a hydroxyl group as described herein are low viscosity liquid products which are storage-stable at room temperature. It has also been found that these modified diisocyanates exhibit lower freezing points than the corresponding unmodified diisocyanates. Advantages of these modified diisocyanates include the ability of store and use them in processes without the need to maintain a >25° C. storage temperature